神经管畸形 (ｎｅｕｒａｌｔｕｂｅｄｅｆｅｃｔｓ ,ＮＴＤｓ)是影响我国和世界人口素质的最常见和最严重的出生缺陷性疾病 ,其病因和发病机理至今仍不十分清楚。已知在孕前 1个月至孕后 3个月补充叶酸可以预防 60 %到 75 %左右的ＮＴＤｓ的发生〔1〕,其余40 %到 2 5 %ＮＴＤｓ Neuraltube defects (NTDs) are the most common and severe birth defects that affect the quality of the population in our country and the world. The etiology and pathogenesis of NTDs are still not clear so far. It is known that the addition of folic acid 1 month before and 3 months after pregnancy can prevent the occurrence of NTDs from 60% to 75% [1] and the remaining 40% to 25% NTDs